FIG. 1 illustrates the construction of a conventional receiver dryer for a refrigeration circuit. The typical refrigeration circuit includes a condenser, an evaporator, a receiver, a compressor and an expansion valve. These items are not shown since the construction and operation of such circuits are known to those of ordinary skill in the art.
As shown in FIG. 1, receiver dryer 10 includes cylindrical body 11 having upper and lower openings. Header 12 is disposed on the upper opening and welded thereto. End or bottom plate 15 is disposed on the lower opening and is also welded to body 11. Header 12 comprises cover plate 121 having a central opening through which connecting portion 122 extends, fluid inlet port member 123 and fluid outlet port member 124. Both fluid inlet and outlet port members 123, 124 are fixed to the central opening through connecting portion 122. Connecting portion 122 includes first and second tubular portions 122a and 122b which allow fluid communication between the interior of cylindrical body 11 and fluid inlet and outlet port members 123 and 124, respectively. Sight glass 13 is placed on the outer opening of second tubular portion 122b of connecting portion 122. Fluid outlet pipe 14 is fixed on the inner opening of second tubular portion 122b. Terminal end 141 of fluid outlet pipe 14 extends into the lower portion of the interior of cylindrical body 11.
Cylindrical body 11 is sectionally divided into three chambers. Upper and lower chambers 111 and 112 are separated by central chamber 113. Central chamber 113 is defined by divider walls 161 and 162 which include a plurality of apertures. Filters 161a and 162a for removing dirt are respectively disposed on the inner surfaces of divided walls 161 and 162 to oppose each other. Desiccant 16 is disposed within central chamber 113 for removing water from the refrigerant.
When the above-mentioned receiver dryer is disposed within a refrigeration circuit, liquid refrigerant is introduced into upper chamber 111 through fluid inlet port member 123 and first tubular portion 122a. Liquid refrigerant in upper chamber 111 flows into central chamber 113 through the apertures of divider wall 161 and filter 161a. Dirt and other foreign particles are removed from the liquid refrigerant by filter 161a. Water is removed from liquid refrigerant by desiccant 16 contained in central chamber 113. Any remaining dirt or foreign particles are further removed from the liquid refrigerant by filter 162a as liquid refrigerant flows from central chamber 113 into lower chamber 112 through the apertures of divider wall 162 and filter 162a. Liquid refrigerant is stored in lower chamber 112 and separates into both gaseous and liquid phases.
Liquid refrigerant stored in lower chamber 112 is sucked out through terminal end 141 of fluid outlet pipe 14 and then flows to the refrigerant circuit through second tubular portion 122b and fluid outlet port member 124.
As mentioned above, a receiver dryer operates to remove water, dirt and other foreign particles from the liquid refrigerant. Further, the receiver dryer separates the refrigerant into both gaseous and liquid phases. Changes in the volume of the discharged refrigerant based on changes in the heat load and the rotational speed of a compressor are also compensated for by the receiver dryer.
However, since bottom plate 15 of the receiver dryer is formed with a planar surface, several problems can occur. First, if the volume of the refrigerant stored in lower chamber 112 is small, terminal end 141 of fluid outlet pipe 14 may be positioned at the boundary between the liquid phase refrigerant and the gaseous phase refrigerant. Accordingly, fluid outlet pipe 14 would not only suck liquid refrigerant into the refrigeration circuit, but also gaseous refrigerant. Thus, the refrigerating capacity of the refrigeration circuit including the receiver dryer would thereby be reduced accordingly.
Second, refrigerant flows into lower chamber 112 from central chamber 113 in drops similar to raindrops. Therefore, when the drops of refrigerant fall into lower chamber 112, they cause waves and bubbles to occur in the liquid refrigerant contained in lower chamber 112. Under these conditions, gaseous and liquid refrigerant may easily flow into terminal end 141.
In the past, these problems have been overcome by increasing the volume of the refrigerant used. This thus prevents the occurrence of waves and bubbles in the refrigerant. However, the volume of the refrigerant cannot be reduced below a certain point. Thus, the size of the receiver dryer must be maintained relatively large compared to the refrigeration circuit.